Collagenase plays a prominent role in melting of the mammalian cornea consequent to injury or disease. It is our purpose to examine the regulatory factors controlling the production and activity of mammalian corneal collagenase in terms of cellular interactions between epithelium and stromal keratocytes. We have demonstrated stimulation of corneal stromal cells to produce collagenase, by epithelium cell conditioned-medium. We are establishing the conditions for production of the stimulator substance and will isolate and characterize it. We also hope to identify the particular epithelial cells which make stimulator and those cells in the stromal population which produce the enzyme.